Is Prolog still used in AI?
Remembering that artificial intelligence has been an academic endeavour for the longest time, Prolog was amongst one of the early languages used as part of the study and implementation of it. It has rarely made its way into large commercial applications, having said that, a famous commercial implementation is in Watson, where prolog is used for NLP.

The University of Edinburgh contributed to the language and it was sometimes referred to as "Edinburgh Prolog". It is still used in academic teachings there as part of the artificial intelligence course.

The reason why Prolog is considered powerful in AI is because the language allows for easy management of recursive methods, and pattern matching.

To quote Adam Lally from the IBM Thomas J. Watson Research Center, and Paul Fodor from Stony Brook University:


  the Prolog language is very expressive allowing recursive rules to represent reachability in parse trees and the operation of negation-as-failure to check the absence of conditions.